1. Field of the Invention
The present invention relates to a new and improved receiver coil or receiver coil arrangement for a programmable projectile fuze comprising a coil core upon which there is located a winding or coil.
2. Discussion of the Background and Material Information
A programmable projectile fuze, for example as disclosed in the published European Patent Application No. 0,300,255, published Jan. 25, 1989 and the cognate U.S. Pat. No. 4,862,785, granted Sep. 5, 1989, comprises an apparatus for setting a counter for triggering a fuze, especially a delayed action or time fuze, located in the projectile after firing of such projectile. The counter is inductively set by a transmitter coil secured forwardly or downstream of the muzzle of the weapon by means of a receiver coil located within the projectile. There is also provided an apparatus for measuring the muzzle velocity of the projectile, in order to set or adjust the counter for triggering the delayed action fuze as a function of the muzzle velocity of the projectile. The receiver coil is mounted upon a coil body.
In order to be able to set or adjust the delayed action or time fuze with the requisite accuracy, at least 12 bits must be transmitted from the transmitter coil to the receiver coil. Assuming that the projectile has a muzzle velocity of, for example, about 1200 meters per second, then the flight of the receiver coil of the projectile through the transmitter coil secured at the muzzle of the weapon barrel occurs in a relatively short amount of time, so that only very little time is available for transmission of data or information from the transmitter coil to the receiver coil. Therefore, high frequencies are required for the transmission of such data or information.
It has now been found that with a coil core formed of steel, there is possible the transmission of this data from the transmitter coil to the receiver coil or receiver coil arrangement, but such results in an undesired increase in the weight of the projectile fuze. In order to reduce the weight of the projectile fuze in the projectile the coil core can be formed of aluminum. However, when this is done, then:
(a) the induced voltage in the case of an aluminum core is appreciably smaller than for an iron core; and
(b) the positive and negative amplitudes of the induced voltage are asymmetrical in the case of an aluminum core and not of the same magnitude in opposite directions.